This investigation focuses on the physiologic and pathologic effects of thermal stimuli in normal man and in patients with airway disease. The tracheobronchial tree has multiple protective functions. Among them is the limitation of heat and water loss to the atmosphere during periods of high ventilation. One area about which little is known is the mechanism by which upper and lower airways adapt to thermal changes in the environment. For example, most individuals are able to function in extremely frigid surroundings without experiencing major respiratory symptoms or suffering injury to the airways. Unlike the situation in normals, however, patients with airway diseases, such as asthma and chronic bronchitis, do not fare quite as well in these surroundings. Individuals with these illnesses are quite sensitive to cold air and can develop frank respiratory embarrassment with such minimal exposures as entering an air conditioned room or when a cold front passes through their locale. The prevalence of cold induced airway obstruction is quite high. Studies have suggested that 2/3 of all asthmatics may be adversely influenced by cold. The specific aims are to: 1) characterize the pulmonary mechanical effects of cold exposure in health and in subjects with asthma, rhinitis, and chronic bronchitis; 2) determine the mechanism by which skin cooling produces bronchial narrowing; 3) evaluate whether cold interacts with other stimuli to alter upper and/or lower airway function; 4) ascertain if reductions in ambient temperatures change the manner in which inspired air is conditioned, and 5) further explore when, and how nasal obstruction develops with cold air.